You hadn't heard? You should have. In a big victory for the Free Our Data campaign, Gordon Brown has announced that various sets of OS data - presently expected to be vector and raster datasets from 1:25,000 up to 1:50,000 maps will be made available for free reuse, including commercial reuse.

That's going to create the possibility of paper maps created using OS data, but which are tailored to specific niche uses - rambling, climbing, canoeing, horse-riding, tourism, say.

One of the key changes that's expected to take effect is the removal of the "derived data" restriction - under which Ordnance Survey claimed that if you used its maps (physical or digital) to create a dataset, then it had copyright on the new product. Broadly like Microsoft claiming a share on the royalties for your book because you wrote it with Word. (Not exactly, of course, because you generally need a map to view the map-derived dataset.)

The "derived data" argument has been one of the fiercest, if out of sight of most consumers, in the geographic world. Local government didn't like it at all, as we explained in November 2008.

The other interesting question is whether OpenStreetMap will incorporate the released OS data - expected to go under a Creative Commons Attribution licence - into its database. That would at a stroke mean that it will cover the whole of Britain. (OSM will, we're sure, want to wait until it sees the precise details of the licences and the datasets to comment.)

But we're definitely interested to hear how you'd like to see the OS data used.

The details of how the release of this data haven't been released either, but my understanding is that it will receive direct funding from the Treasury, which has made a financial commitment to cover the revenue lost from selling those datasets - reckoned to be about £20m. That still leaves the OS's large-scale MasterMap as a paid-for product, producing about £80m of revenue, and a good - lion's? - share of its profits.

The other question is what will happen to the traditional OS maps. We expect to have more on that next week.